Pink Rot of Tubers (fungi - Phytophthora parasitica and P. cryptogea): Diseased tubers are spongy and initially discolored around the point of stolon attachment. Later, they become discolored around the buds and lenticels. The internal tissues appear cream-colored when cut, but turn salmon pink after 15 - 20 minutes. They gradually become darker, turning black after about 1 hour. Diseased potatoes have been observed in the Texas High Plains primarily in furrow irrigated fields with clay soils. Control includes selecting sites with good soil drainage and avoiding excessive irrigation late in the growing season.
